1. Feature Of The Week: 3D Polymer Weld Seam Characterization Based on OCT Laser Transmission Welding Applications

    Plastics have low weight but a high weight to strength ratio and a good corrosion resistance allied to a high degree of freedom on its form design. These characteristics lead plastics to be used in several technical systems with high production and application requirements. Herewith the complete production chain of these components as well as their integration in technical systems are also subjected to high standards.

    The joining of plastics and polymers is an important step in this process chain, as often at this stage pre-processed parts with a high added value are machined. Especially in high performance production chains the usage of bonding techniques based on laser transmission welding is technically and financially superior to other methods. This occurs due to its high precision and automation capacity, contact-free, hygienic and absolutely particle-free operation, low temperature and vibration influence, form freedom, as well as short process cycles (no extra cleaning or hardening steps) and the possibility of multi-material joining. Examples are in a broad spectrum of industrial branches, e.g. medical devices (filters, microfluidic, lab-on-a-chip, medical packaging), automotive, pharmaceutics, aerospace, electronics and sensors.

    This welding method is affected by different machine, workpiece and environmental related parameters, which influence the process stability and product quality. For manufacturing precise and high added value parts with minimal scrap levels and high throughput, the tolerable process parameter deviations are small. To secure process stability and product quality for long production periods an in-process quality assurance is desirable. Most monitoring systems in this field are based on displacement measurement, pyrometers systems or destructive methods. But these methods have limited usage. No quantitative information concerning the real manufactured weld seam as geometry or geometry deviation (e.g. seam narrowing or interruption) or the presence of pores and / or blowholes is obtained. Therefore up to now false friends rather weld seams with a leakage can be produced without being detected by setting path measurements or pyrometers, which is unacceptable e.g. for medical or pharmaceutical applications.

    In order to solve these issues an optical measurement system based on the optical coherence tomography (OCT) is presented. The proposed solution is able to be applied in standard laser transmission welding applications as well as in fields, which are not covered by the state of the art feedback control technologies for laser transmission welding, as processes using joining partners with thicknesses of more than 2 mm or with glass fiber reinforcement levels over 30 % per weight as well as applications with high demands concerning leak tightness.

    This work presents on one hand the evaluation of the OCT technology as a tool for the weld seam characterization and as a quality assurance tool. On the other hand, a solution concept for the inline process monitoring based on this technology for the laser transmission welding will be presented.

    For more information see recent Article or visit this website. Courtesy Guilherme Mallmann and Robert Schmitt from RWTH Aachen University. To share this article click Here.
  2. Recent Articles From Around The Web

    1. Are the findings of optical coherence tomography sufficient for the evaluation of the safety and efficacy of the next generation of drug eluting stents

      Are the findings of optical coherence tomography sufficient for the evaluation of the safety and efficacy of the next generation of drug eluting stents

      The cr8 stent is a next generation drug eluting stent (DES) with a polymer free abluminal reservoir drug release system. It uses an organic fatty acid permeation enhancer and a carbon surface to increase biocompatibility. The fatty acid enhancer may have beneficial effect in improving drug delivery in diabetic patient where neointimal hyperplasia is particularly problematic[1]. These types of design features are exciting new developments and may provide novel strategies for improving the safety and efficacy of the next generation of coronary stents.

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    2. Optical Coherence Tomography Imaging of Presumed Sarcoid Retinal and Optic Nerve Nodules

      Optical Coherence Tomography Imaging of Presumed Sarcoid Retinal and Optic Nerve Nodules

      Purpose : To characterize nodular lesions of the retina and optic nerve with spectral-domain optical coherence tomography (SD-OCT) in patients with sarcoidosis. Methods : This is a retrospective series of 6 eyes from 5 patients with an established diagnosis of sarcoidosis, with clinically detected nodules of the optic nerve or retina. All lesions were imaged with fundus photography and SD-OCT on presentation, and followed with serial imaging after treatment with corticosteroids and/or immunomodulatory therapy. Results : Spectral OCT through the lesions revealed nodular hyperreflective processes obscuring the retinal layers or optic cup, with local structural changes, including subretinal and intraretinal fluid. After ...

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    3. Insights into the spatial distribution of lipid-rich plaques in relation to coronary artery bifurcations: an in-vivo optical coherence tomography study

      Insights into the spatial distribution of lipid-rich plaques in relation to coronary artery bifurcations: an in-vivo optical coherence tomography study

      Objectives: The aim of this study was to investigate the spatial location of vulnerable plaques at coronary artery bifurcations using frequency domain-optical coherence tomography. Background: In-vivo data on geometric location of vulnerable plaques in relation to coronary bifurcation are limited. Materials and methods: A total of 40 patients with left anterior descending artery bifurcation were studied. Plaque characteristics in five regions in relation to a side branch were compared: opposite flow divider (OFD); bifurcation site (BF); main branch side proximal (MBP); side branch side proximal (SBP); and flow divider (FD). Frequency domain-optical coherence tomography was used for plaque characterization. Results ...

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    4. Optical coherence tomography imaging of inoperable chronic thromboembolic pulmonary hypertension treated with refined balloon pulmonary angioplasty

      Optical coherence tomography imaging of inoperable chronic  thromboembolic pulmonary hypertension treated with refined balloon  pulmonary angioplasty

      Chronic thromboembolic pulmonary hypertension (CTEPH) usually results from the chronic obstruction of the pulmonary arteries by unresolved thromboemboli following acute pulmonary embolism (PE). Surgical pulmonary endarterectomy is the first-line therapy in CTEPH, however some patients are inoperable due to high perioperative risk or distal localization of thrombi. Balloon pulmonary angioplasty (BPA), a new emerging therapy, with growing evidence has been adopted in this group of patients [1]. Recently refined BPA has been described with use of new imaging modalities, which markedly improved both BPA efficacy and safety [2,3]. Optical coherence tomography (OCT) is a novel, promising tool and was ...

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    5. Optical coherence tomography and confocal microscopy following 3 different protocols of corneal collagen-crosslinking in keratoconus.

      Optical coherence tomography and confocal microscopy following 3 different protocols of corneal collagen-crosslinking in keratoconus.

      Purpose: To compare the efficacy and early morphological changes in the cornea following conventional (C-CXL), transepithelial by iontophoresis (I-CXL), and accelerated collagen cross-linking (A-CXL) in keratoconus. Methods: 45 eyes of 45 patients with progressive keratoconus who underwent corneal collagen crosslinking (CXL) were divided into 3 groups: C-CXL (n=15), A-CXL (n=15) and I-CXL (n=15). Patients were examined before surgery and at 1-month, 3-month, and 6-month intervals following surgery. Density of corneal sub-basal nerves, anterior and posterior keratocytes, corneal endothelium, demarcation line depth and maximal simulated keratometry values (Kmax) were all assessed. Results: Compared with preoperative values, the mean ...

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    6. Lipid-rich plaque in possible coronary sequelae of Kawasaki disease detected by optical frequency domain imaging

      Lipid-rich plaque in possible coronary sequelae of Kawasaki disease detected by optical frequency domain imaging

      Potential risk for early development of atherosclerosis in patients with antecedent- Kawasaki disease (KD) is now attracting more attention. A 47-year-old man was admitted to our hospital because of calcification exclusively in the proximal segment of left anterior descending coronary artery (LAD) on chest CT. Coronary CT revealed a severe stenosis at the inlet of the aneurysm with eggshell-like calcification in the proximal LAD, highly suspecting the presence of coronary sequelae of KD. During the rotational atherectomy-based interventional procedure, optical frequency domain imaging, a new generation of optical coherence tomography, clearly depicted lipid deposition in the culprit lesion.

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    7. Peripapillary rat sclera investigated in vivo with polarization sensitive optical coherence tomography

      Peripapillary rat sclera investigated in vivo with polarization sensitive optical coherence tomography

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    8. Graphene Sensors Stimulate Neurons Optically And Electronically

      Graphene Sensors Stimulate Neurons Optically And Electronically

      While electrical sensing is a mainstay of neurological studies, optical methods have recently started to become more prevalent. A new sensor system from DARPA now allows both modalities to be used together, for greater insights into neural structure and function. Electrical impulses are the primary way that neural cells communicate. Historically, electrical studies have enabled the evaluation of neural cell communication. Generally, the understanding of neural cells that was gained by studying electrical impulses was garnered through correlation studies, so a direct link was not possible to prove relationships between neural cell electrical activity and behavior. Recently, the development of ...

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    9. Enhanced depth imaging optical coherence tomography of congenital cavitary optic disc anomaly (CODA)

      Enhanced depth imaging optical coherence tomography of congenital cavitary optic disc anomaly (CODA)

      Aim To report the finding of extension of the 4th hyper-reflective band and retinal tissue into the optic disc in patients with cavitary optic disc anomalies (CODAs). Methods In this observational study, 10 patients (18 eyes) with sporadic or autosomal dominant CODA were evaluated with enhanced depth imaging optical coherence tomography (EDI-OCT) and colour fundus images for the presence of 4th hyper-reflective band extension into the optic disc. Results Of 10 CODA patients (18 eyes), five patients (8 eyes) showed a definite 4th hyper-reflective band (presumed retinal pigment epithelium (RPE)) extension into the optic disc. In these five patients (seven ...

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    10. Spectral-Domain Optical Coherence Tomography of Sympathetic Ophthalmia With Dalen-Fuchs Nodules

      Spectral-Domain Optical Coherence Tomography of Sympathetic Ophthalmia With Dalen-Fuchs Nodules

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      Platform to investigate aqueous outflow system structure and pressure-dependent motion using high-resolution spectral domain optical coherence tomography

      The aqueous outflow system (AOS) is responsible for maintaining normal intraocular pressure (IOP) in the eye. Structures of the AOS have an active role in regulating IOP in healthy eyes and these structures become abnormal in the eyes with glaucoma. We describe a newly developed system platform to obtain high-resolution images of the AOS structures. By incorporating spectral domain optical coherence tomography (SD-OCT), the platform allows us to systematically control, image, and quantitate the responses of AOS tissue to pressure with a millisecond resolution of pulsed flow. We use SD-OCT to image radial limbal segments from the surface of the ...

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      Anisotropic polyvinyl alcohol hydrogel phantom for shear wave elastography in fibrous biological soft tissue: a multimodality characterization

      Shear wave elastography imaging techniques provide quantitative measurement of soft tissues elastic properties. Tendons, muscles and cerebral tissues are composed of fibers, which induce a strong anisotropic effect on the mechanical behavior. Currently, these tissues cannot be accurately represented by existing elastography phantoms. Recently, a novel approach for orthotropic hydrogel mimicking soft tissues has been developed (Millon et al 2006 J. Biomed. Mater. Res. B 305–11). The mechanical anisotropy is induced in a polyvinyl alcohol (PVA) cryogel by stretching the physical crosslinks of the polymeric chains while undergoing freeze/thaw cycles. In the present study we propose an original ...

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    13. Comparison of optical coherence tomography and histopathology in quantitative assessment of goat talus articular cartilage

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      Background and purpose — Optical coherence tomography (OCT) is a light-based imaging technique suitable for depiction of thin tissue layers such as articular cartilage. Quantification of results and direct comparison with a reference standard is needed to confirm the role of OCT in cartilage evaluation. Materials and methods — Goat talus articular cartilage repair was assessed quantitatively with OCT and compared with histopathology using semi-automated analysis software. Osteochondral defects were created centrally in goat tali with subsequent healing over 24 weeks. After sacrifice, the tali were analyzed using OCT and processed into histopathology slides. Cartilage thickness, repair tissue area, and surface roughness ...

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    14. Comparison of multifocal visual evoked potential, static automated perimetry, and optical coherence tomography findings for assessing visual pathways in patients with pituitary adenomas

      Comparison of multifocal visual evoked potential, static automated perimetry, and optical coherence tomography findings for assessing visual pathways in patients with pituitary adenomas

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      Mentions: Fudan University
    15. Reproducibility of Spectral-domain Optical Coherence Tomography RNFL Map for Glaucomatous and Fellow Normal Eyes in Unilateral Glaucoma

      Reproducibility of Spectral-domain Optical Coherence Tomography RNFL Map for Glaucomatous and Fellow Normal Eyes in Unilateral Glaucoma

      Purpose: To compare the reproducibility of the optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) thickness map between glaucomatous and fellow normal eyes of unilateral glaucoma patients. Methods: In this prospective case-control study, Cirrus HD-OCT was performed for 79 unilateral glaucoma patients 3 times on the first visit and on 3 subsequent visits within a 2-month period. Test-retest standard deviation (TRT-SD) and tolerance limit based on the 1.645x[square root]2xTRT-SD formula were derived for RNFL thicknesses at the respective superpixels of the RNFL thickness map. Results: The TRT-SDs and tolerance limits of the glaucomatous eyes (TRT-SD: 2 ...

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    16. See all articles
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  2. Organizations in the News

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    1. (4 articles) Carl Zeiss Meditec
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    1. (2 articles) Zeiss Cirrus HD-OCT
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